1. Field of the Invention
The present invention relates to a mixing valve which mixes fluids supplied from respective ports.
2. Description of the Related Art
A mixing valve has been used to mix fluids supplied from respective ports for obtaining a mixture having a desired composition.
As shown in FIGS. 8 and 9, a conventional mixing valve 1 includes a first port 2a supplied with a fluid A and a second port 2b supplied with a fluid B in a valve body 3. Further, the valve body 3 has a third port 2c discharging a mixed fluid obtained by mixing the fluid A supplied from the first port 2a and the fluid B supplied from the second port 2b. 
A first ON/OFF valve 5a and a second ON/OFF valve 5b are juxtaposed with each other on the valve body 3. The first ON/OFF valve 5a opens/closes a flow passage for the fluid A supplied from the first port 2a under the action of a pilot pressure introduced from a first pilot port 4a. The second ON/OFF valve 5b opens/closes a flow passage for the fluid B supplied from the second port 2b under the action of a pilot pressure introduced from a second pilot port 4b. 
Then, the pilot pressure displaces a first valve plug 6a of the first ON/OFF valve 5a upwardly to give the valve-open state and displaces a second valve plug 6b of the second ON/OFF valve 5b upwardly to give the valve-open state. Accordingly, the fluid A supplied from the first port 2a and the fluid B supplied from the second port 2b are mixed with each other, being discharged from the third port 2c. 
An agitator 7, which uniformly stirs a mixed fluid discharged from the third port 2c, is disposed downstream of the mixing valve 1. The agitator 7 is elongated and kept substantially vertical. The agitator 7 has an inlet port 8a at the upper end and an outlet port 8b at the lower end. A fluid passage 9 is formed between the inlet port 8a and the outlet port 8b. The fluid passage 9 functions such that the flow of the mixed fluid supplied from the inlet port 8a is continuously reversed in the clockwise direction and the counterclockwise direction to effect the agitation by alternately inverting the twist direction for adjoining cylindrical members.
However, the conventional mixing valve 1 for mixing the fluid A and the fluid B requires the separate agitator 7 for uniformly stirring the mixed fluid, increasing an installation space. The elongated agitator 7 downstream of the mixing valve 1 requires a large vertical space, making it impossible to use the agitator 7 in an installation environment in which the vertical space is narrow.
Further, in the conventional mixing valve 1, the fluid A and the fluid B which are supplied are merely mixed with each other, making it impossible to uniformly mix the fluid A and the fluid B.
It is a general object of the present invention to provide a mixing valve which reduces an installation space, thereby enabling a space to be effectively used.
A principal object of the present invention is to provide a mixing valve which makes a mixed state of fluids uniform.
According to the present invention, fluids are supplied from respective supply ports and introduced into helical members having ends facing an agitation chamber. The fluids flow helically along helical passages of the helical members into the agitation chamber where the fluids are suitably mixed with each other, enabling the mixed state of the fluids to be uniform.
Further, the present invention does not require any conventional separate agitator downstream of the mixing valve. Therefore, the installation space is narrowed, enabling the space to be effectively used.
The above and other objects, features, and advantages of the present invention will become more apparent from the following description when taken in conjunction with the accompanying drawings in which a preferred embodiment of the present invention is shown by way of illustrative example.